Previous automotive systems (e.g., ESP: electronic stabilizing program), restraint systems, and navigation systems are limited to the detection of planar movements of the vehicle and involve one-dimensional or two-dimensional measurement tasks. With advances in automotive engineering, there is a demand for detecting the spatial state of driving or motion. A variety of additional information may be made available through central detection of the spatial movement state. This information includes the inclination of the vehicle, which makes it possible to regulate the lighting, the displacement of the shift point of automatic operation on an inclination, etc., detection of a rollover and thus a more targeted deployment of airbags, recognition of steep curves, which may be used to improve the ESP algorithm, etc.
In the case of safety-relevant automated systems such as airbag systems and ESP, special emphasis is placed on the availability and correctness of the signals. Therefore, redundancy concepts are required for such systems if the additional information is used in the systems.
As mentioned above, detection of the planar driving state by acceleration sensors and rotational rate sensors is conventional. Such sensor systems for detection of the planar movement state have already been produced by the applicant for a long time. One of these systems detects the longitudinal and transverse acceleration of the vehicle as well as rotation about a vertical axis and calculates from this the planar movement state of the vehicle in a local vehicle estimator.
Other systems detect only planar movement states. Since vehicles in general and motor vehicles often execute spatial movements in reality, the above-mentioned conventional detection systems always measure only the projection of the spatial movement onto a constantly changing plane which represents the vehicle base area. Interpretation of these measurement results may result in errors in determination of the driving state. These errors are small in normal driving states but in various driving states such as driving on a steep curve, driving on a steep inclination, rollover of the vehicle, these errors become extremely large and may have a misleading effect on the vehicle systems such as ESP and restraint systems.
To avoid such malfunctions of the automotive systems, complex algorithms have been used in the past and the movement states in fallback planes producing the errors have been treated separately, e.g., in a separate steep curve detection. In other cases, spatial movement states are detected only poorly or not at all such as a vehicle rollover in the case of restraint systems, so that in such a state the airbags are frequently not deployed.
In the past more and more sensors have been installed in vehicles for detection of such situations. For example, it is already apparent with the ESP system that detection of such exceptional cases of movement states is complex.